Question for coolant guru's

[salukispeed]

I have been around cars and trucks and done all my own repairs for 45+ years. Back when GM started using the DEX-Cool I started seeing crunchy crusty break down crud that, I read was from the systems not completely full so Air was introduced and constantly blended and the coolant would break down and fill the system with crap. I was also told that it is the blended air that is the main issue that destroys the additives and results in plugged passages, heater cores, corrosion and gasket failures. Most manufactures now use these long life coolants. What I find odd is after only 4+ years my 1987 Ford E350 on a Motorhome chassis went from nice clean green fluid to complete garbage crud and sediment just like the DEX cool. It has a radiator that does not lend its self to a recovery bottle easily so it runs about 1-1 1/4 down from the top when cool and nearly full at normal temps. Has even the old stand-by green ( Prestone ) now joined the ranks of the sealed system only. You can no longer dump and flush irresponsibly like back in the day and to capture the 5 gal in the system and many flush gallons is a real challenge. I put block drains with nipples for hoses to make it easier but it still bites. and now I need to find a recycler for 35+ gal of the crud.